This paper presents an experiment for measuring the acoustic energy loss in the sand bed in water tank.

介绍了测量声波穿透沙层后能量损失的水池实验。

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Some engineers suggest that this period be extended to allow a sand bed to rest for a month after the sludge cake has been removed.

一些工程师建议这段时间应该被延长，以便沙床能够在泥浆块被移除后休息一个月的时间。

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The two-phase flows over the sand bed and in the pipe are simulated, the different distributions of volumetric fraction are found and analyzed.

计算了沙层上及直管中的两相流的流动，发现了颗粒浓度两种截然不同的分布，并对此进行了分析。

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They claim holes left in the sea bed from ships extracting gravel and sand are being refilled with sand from the shoreline of their local beaches.

BBC: Dredging 'causing erosion' claim

Opportunity has been trundling around Mars ever since, though it was designed for only a ninety-day mission. (Spirit got stuck in a sand trap in 2009 and quit transmitting nearly a year later.) It never found the lake bed, or organic material of any kind.

NEWYORKER: The Martian Chroniclers